Electromagnetic waves may be transferred from place to place through a conductor. In wired transmission, the conductor is usually a wire or other solid substance. In wireless transmission, the conductor is usually an ambient substance, such as air, water, etc. A transmitter typically converts electrical energy into a signal, which is then broadcast via carrier wave through an antenna to a receiver's antenna. Repeaters, middle stations, etc. may be used as intermediates in the transmission to sustain the integrity of the transmitted wave.
The electrical energy input into a transmitter usually results from some intelligence being generated by a sender, such as voice, data, etc. This intelligence is modulated onto a carrier wave by the transmitter. The now modulated carrier wave is the transmitted electromagnetic signal. A receiver may then demodulate the signal, by deconstructing the modulated carrier wave into a copy of the initial intelligence sent by the transmitter.
Various techniques are used to modulate the carrier wave. For example, carrier waves in wireless transmission may be modulated on to signals by varying wave characteristics, such as amplitude, frequency and phase. Linear techniques typically modulate frequency and/or phase and amplitude characteristics of a signal. Non-linear techniques typically modulate frequency and/or phase characteristics of a signal.
Digital or analog techniques or a combination of both may be used with linear or non-linear techniques. The nature of the signal—its envelope—may determine whether linear or non linear techniques are used. Constant envelope signals typically use a non-linear transmit technique while a more linear transmit technique is typically used for non-constant envelope signals.
These techniques are not necessarily distinct. For example, transmitters may need to support a combination of constant and non-constant envelope schemes such as when a transmitter is used for multiple modes of operation (e.g., GSM and EDGE). The need to support multiple pulse processing schemes has led to costly and inefficient architectures. Traditionally, multiple modulation schemes in a single transmitter have been provided through either single modulation architectures, which provide less than optimal solutions, or multiple modulation architectures, which increase cost and complexity of the transmitter.
Accordingly, it would be helpful to the art of electromagnetic transmission if transceiver, transmitter and receivers systems, methods and articles of manufacture could be provided that facilitate multiple modulation schemes.